The present invention relates to a process for the production of polymeric polyols which comprises the steps of saponifying low molecular weight ethylenesaturated carboxylic acid vinyl ester copolymers, and then carrying out an alkylene oxide-addition operation. More specifically, the invention relates to a process for producing polymeric polyols which are useful as starting materials in the production of synthetic resins, for instance, as polyol components of saturated polyesters, polyurethanes and the like, and as additives, including bloom inhibitors for synthetic rubbers such as SBR (styrene-butadiene rubber), NBR (acrylonitrile-butadiene rubber), CR (chroloprene rubber), EPDM (ethylene-propylene-diene terpolymer), etc., antistatic agents, antifogging agents, lubricants, and workability improvers, for synthetic resins such as polyethylenes, polypropylenes and the like, and also as polymeric solid electrolytes, wax modifiers, bonding agents for inorganic materials, and the like.
Saponification products of ethylene-saturated carboxylic acid vinyl ester copolymers are known, and polymeric polyols, which have been produced by an alkylene oxide-addition reaction of such saponification products, are also known.
For instance, Japanese Patent Specification KOKOKU No. Sho 52-17558 (1977) discloses a process for the saponification of ethylene-saturated carboxylic acid vinyl ester copolymers, wherein a low molecular weight ethylene-vinyl ester copolymer, having a molecular weight of from 800 to 4000, is dissolved in a solvent such as xylene, and the resulting solution is saponified with the aid of methanol and catalysts in an autoclave or tower type reactor to form a glossy wax product.
U.S. Pat. No. 2,434,179 discloses a process for producing polymeric polyols by adding an alkylene oxide to a saponification product of ethylene-saturated carboxylic acid vinyl ester copolymers, wherein an alkylene oxide such as ethylene oxide is added to a saponification product of ethylenevinyl acetate copolymers having an ethylene/vinyl acetate molar ratio of from 1/25 to 8/1.
However, the known methods mentioned above comprise independently effecting the saponification and the alkylene oxide-addition. So, these methods are not highly effective and not economical for the production of polymeric polyols by saponifying a starting ethylene-saturated carboxylic acid copolymer and then by effecting an alkylene oxide-addition reaction. Further, the known processes require the use of a large amount of alkali catalysts, so that the resultant polymeric polyols have an undesirably high alkali residue content. Such polyols are not suitable for use in certain fields.
Japanese Patent Specification KOKOKU No. Sho 52-17558 (1977) discloses a process for the saponification of ethylene-saturated carboxylic acid vinyl ester copolymers, wherein the saponification reaction is carried out in a solution of the reactant in an organic solvent such as xylene having a concentration of up to 60% by weight. So, in this process, it is a serious problem to recover the solvent used.
Alkali catalysts are effective in each of the saponification reaction and the alkylene oxide-addition reaction. However, if one kind of alkali catalyst is used in both the saponification reaction and the alkylen oxide-addition reaction, it will be observed that the reaction velocity of any one of these two reactions will be undesirably low. To eliminate this drawback, it is necessary to use such a catalyst in a large amount. As a result of this, the polymeric polyol products will have a high alkali salt residue content, and it is very difficult to remove the alkali salt residues.